﻿using System;

class TrapezoidArea
{
    static void Main()
    {
        Console.Write("Enter the first side of the trapezoid:\r\na = ");
        double a = double.Parse(Console.ReadLine());
        Console.Write("Enter the second side of the trapezoid:\r\nb = ");
        double b = double.Parse(Console.ReadLine());
        Console.Write("Enter the height of the trapezoid:\r\nh = ");
        double h = double.Parse(Console.ReadLine());
        double area = ((a + b) / 2) * h;
        Console.WriteLine("The trapezoid's area is {0}.", area);
    }
}
